Apparatus for analyzing gases



A e 6g June 13, 1939. v 'v o. G. BENNETT 2,162,395

APPARATUS FOR ANALYZING 4GASES I Filed July l, 1956 2 Sheets-Sheet l l INVENTOR. OWEN G. Bau Na'rr 'A 4 ATTORNEYS.

June 13, 1939. l o. G. BENNETT 2,162,395

APPARATUS FOR ANALYZING `GASES Filed July 1, 1936 2 sheets-sheet 2 2 28 2? j INVENTOR. IZ JMA 'OWLN Gr. BENNETT BYfb *I E zg z 4 ATTORNEYS,

Patented June 1.3,'1939 UNITED STATE nrrrntrrius Fon ANALYzmG GASES owen G. Bennett, Pittsburgh, Pa., assigner to Catalyst Research Corporation, Pittsburgh, Pa., `a corporation of-Maryland i Appucationuuly 1, 193s, serial No. 88,351

4 Claims,

diffusionanalysis gases are ilowed across one side of a diffusion diaphragm and the pressure change caused-on the opposite side of the diaphragm by the diil'usion of a gas or gases there- -iso through is then measured. The pressure created withinany given period of timeA by diffusion of .a gas in this manner depends upon its diffusion rate, and the latter bears a direct relation to the density of the'gas. Consequently, some gases will create more pressure than others, and from the pressure registered various vvinformation pertaining to gases can be rapidly, accurately and readily determined. For examp1e, by diusion it is a simple'matter to fractionate a gaseous mixture to separate one or more constituents, to rind the'relative density of a gas, or to determine the composition of gaseous mixtures.

One eld in which the possibilities for gas analyzing apparatus are especially great is that relating to the analyzing of exhaust gases of internal combustion engines. The relative proportions of the constituent gases of an exhaust gas indicate whether or not the engine carburetor is set properly and thereby whether fuel is being wasted, power is being lost, or the engine is running eiilciently. However, the apparatus used for that purpose heretofore leave much to be desired in cost, simplicity and accuracy.

It is among the objects of this invention to provide' apparatus for analyzing gases, and particularly for determining the composition of a gaseous mixture, which is light, compact, simple in construction and operation, operable by un' skilled persons, quickly responsive, and accurate and dependable under all normal conditions. A more speciiic object is to provide a simple apparatus for quickly and accurately analyzing the4 exhaust gases of internal combustion'engines.

The preferred embodiment of .the invention is illustrated in the accompanying drawings in which Fig. 1 is a central vertical section through the analyzer; Fig. 2 is a plan viewthereof; Fig. 3

is a plan view, taken on line III-III of Fig. 1, of the lower plate serving as part of the valve forming the central portion of the apparatus; Fig. 4 is a bottom plan view, taken on line IV-IV of Fig. 1, of the upper plate of the valve; Fig. 5 is an enlarged vertical section taken on line V-V of Fig. 3; Fig. 6 is a plan view ofthe two valve plates, taken -,on line VI--VI of Fig. l, showing them in the position they occupy, during gas analysis; Figs. 7 and 8 are vertical sections taken on lines VII-VII and VIII--VIIL respectively, of Fig. 6; Fig. 9 is a plan view similar to Fig. 6, but showing the two valve plates in the position they occupy whenthe apparatus is being prepared for the-next analysis; and Fig. 10 is a vertical section taken on the line X--X of Fig. 9. In accordance with this invention, a valve is formed from two at plates disposedface to face in sealing engagement and adapted to be rotated relative to each other on their common axis between operative and inoperative positions. 011e of the plates -is provided with an opening with which a diffusion member is associated, while the two plates are provided with a plurality of passages thatl registeronly when the plates are in operative position to form a continuous passage through'which gases are admitted to one side of the diiIusion member. The opposite side of the diffusion member is in communication with a pressure-responsive device that registers the pressure of gases diffusing through the diffusion member. The plates are also provided with a plurality of passages that register only when the plates are in their inoperative position for connecting both sides of the diffusion member with a forced current of pure air to permit the apparatus to be purged between analyses.

In diffusion analysis the diiusionmember initially separates the gases to be analyzedifrom a standard gas such as'air, and a change in pressure on the standard gas side of the member is caused by diffusion of the gas having the least density through the diffusion member before the gas or gases on the opposite side of the member can diffuse through it in the opposite direction. In determining the relative proportions of certain constituent gases of a gaseous mixture an inaccurate result may be obtained if two or more gases diffuse through a diffusion member in the same direction at substantially the same rate, or if besides a gas having less density than the standard gas there is another gas having a greater density than the standard gas so that there is substantially as much tendency for the standard gas to pass through the diiusion member in onedirection as there is for the low density gas to do so in the opposite direction.

For example, the exhaust gas of an internal 4combustion engine comprises largely carbon dioxide, carbon monoxide, nitrogen, oxygen and hydrogen, and if the proportion of hydrogen in the mixture is known the composition of the mixture can be determined. The densities of L' carbon monoxide, oxygen and nitrogen are s ubstantially the same as that of air which may conveniently be used as the standard gas, but hydrogen is o f less density and carbon dioxide is of greater density.- If a mixture f these gases were owed across a diffusion member the hydrogen would tend to diffuse through the member more rapidly than the`air on the opposite side would diffuse in the opposite direction, but

the air would tend to diffuse through the member .more rapidly than the carbon dioxide on the opposite side. This would result in a' tendency for the gases on the two sides of the diusion member to balance and show but little sides in the removal from the gaseous mixture,

` before it reaches the diffusion diaphragm, of

Operatively connected to this diaphragm is a any gases, other than the one the proportion of whichf relative to the remaining gases is to be determined, having densities materially different from,that of the standard gas.

Referring to Fig. 1 of the drawings, a valve member is formed from two flat plates I and 2 held face to face by a collar 3 having an inwardly projecting flange 4 engaging the bottom of the 'lower plate, and by a retaining ring 5 threaded in the upper portion of the collar. To` hold the two plates firmly together, but not so tightly that `they can not be rotated relative to each other on their common axis, to open and close various passages with which they are provided, an undulatlng annular spring 6 is compressed between the retaining ring and the outer surface of upperv platev I, hereinafter called a disc, around its thickened central portion. Rotation of the disc relative to the plate is eii'ected by turning collar 3 to which the disc is connected by one or more peripheral lugs 1 (Fig. 4) that register with recesses 3 in the inner wall of the collar. Rotation of the disc in either direction is limited by a pin 3 projecting from its inner face into an arcuate recess III in the plate (Fig. 3).

It is a feature of this invention that the diffusion member 'is mounted in the valve, rather than outside of it. Accordingly, as shown in Figs. 1 and 4, the disc is provided with a relatively large central opening I'I extending axially therethrough with its inner end enlarged to form an annular recess for receiving the rim I2 of a diffusion diaphragm I3. The rim is provided with openings through which extend screws I4 that `bind it to the disc with a sealing gasket I6 between. The diaphragm, which is thinner than the rim, is

4oil'set from the opposite faces of the rim to space it a short distance from plate12. Although any suitable type of diffusion diaphragm may be used, it is preferred to use one made by compressing finely divided nickel made by distillation of mercury from a nickel amalgam. Such a'dlaphragm is described and claimed in my Patent No. 2,045,379, granted June 23, 1936: l

S'ecured to the outer face of the disc around opening II is a ring I1 t'o which a pressureactuated diaphragm I8 is securely connected.

mechanism I9 of Well-known construction for magnifying the movements of the. diaphragm under-pressure, anddfor indicating those movements by means of a needle 2| which turns on a dial A inwardly through the discA from 22. The pressure meter thus formed is enclosed by a cover 23 screwed to collar 3 and provided in its outer end with a glass window 24 (Fig. 2).

To permit gas that is to be analyzed to iiow through the valve member and across the plate side of the diffusion diaphragm, plate 2, as shown in Figs. 3, 6, and 8, is provided with an inlet passage 26 to the outer end of which the gas is supplied, and the plateand disc are provided with other passages which connect the inlet passage to the-plate side of the diffusion diaphragm when the plates are turned to analyzing position. Thus, in addition to inlet passage 26 the plate is provided with a radial passage 21 which communicates 'at its inner end with an axial passage 28 opening directly below the center of the diffusion diaphragm, and at its outer end portion with two passages 23 and 3I opening to the disc. The inner face of the disc is provided with an arcuate groove 32 (Figs. 4 and 6) which extends from inlet passage 26 to passage 29, so that gas Ventering the inlet passage iiows in thedirection of the arrows between the plate and disc in groove 32 into radial 'passage -21 and up` to the diaphragm through axial passage 23 (Fig. 7). The gas then iiows outwardly across the diaphragm into an annular groove 33 in the plate below the edge of the diaphragm, and out to the atmosphere through one or more radial passages v34 in the plate (Figs. 5 and 7). Whatever gas diffuses through the diaphragm creates pressure between the two diaphragms whereby pressure diaphragm I8 actuates meter mechanism I9 by which the needle is turned on the dial to give a reading.

After the reading has beentaken the disc is turned to its inoperative position, shown in Figs. 9 and 10, wherein disc groove 32 is out of register with plate passages 26 and '23 so that gas can not reach the diffusion diaphragm. While the valve is in its inoperative position the gas entering the inlet passage is led out of the valve through a 'radial groove 36 in the inner face of the-*disc connecting the inner end of the inlet passage to the inner end of an outlet 31 through the plate.

To permit the gas on both sides of the diffusion diaphragm to be swept out of the valve, following an analysis, the inner face of the'disc is provided with'a groove 38 (Fig-4) that connects passage -3I to the inner end of a passage 39 "through the plate which connects at its outer end with suitable means for creating a current of air, such as a, rubber bulb 4I. Extending radially disc groove 33 to opening I I between the two diaphragms ls a duct 412. Extending outwardly from between the diaphragms is a pair of outlet ducts 43 that terminate in a groove 44 in the inner face of the disc that registers with the inner ends of a pair of outlets 46 through the plate. When the bulb is compressed, a current of air is forced in the direction of the arrows through disc groove 38 `and radial plate passage 21 and sweeps the gas from beneath the diaphragm and out through outlet passages 34, and another current oi air is forced through discl duct 42 to sweep the gas between the diaphragms out through the disc outlet ducts 43 and plate outlets 46. Leakage of gas orl air between the disc and plate is prevented by a sealing liquid between them.

As previously indicated herein. in a mixture a constituent gas, other than the one the proportion of which in the mixture is to be determined, having a density materially diiferent than that of the standard gas used, will cause apparatus of barrel is closed by a screw cap 52 (Fig. 1) having a passage 53 therethrough adapted to be connected by a hose or the like to the source of lgas to be analyzed, such as to the exhaust pipe of an internal combustion "engine.

Removably disposedin the barrel in the path of gas passing through it is a charge of material 54 of a character adapted to absorb'the gas thatv is to lbe removed. This material is preferably contained in a cartridge 56 so.that it can be easily handled! VThe ends of the cartridge are closed by porous cloth pads 51 and screens 58 to hold the material in place withoutv interfering with the passage of gas through it. Disposed between the screw cap and the rim of the cartridge is a gasket 59 to insure that none of the v gas will escape past the cartridge, When this apparatus is to be used for analyzing exhaust gases, in which carbon dioxide is the objectionable gas that prevents accurate analysis, the cartridge is'lled with a carbon dioxide absorbing material such as soda lime which is suitable for temperatures above freezing. In sub-freezing temperatures it may be found to be desirable to use some other carbon dioxide absorbing material.`

As it requires only a very small amount of gas to give a reading, the inner end'of cap passage 53 is restricted, as by a plug 6i, and the cap is provided with an outlet duct62 leading laterally from the passage to the atmosphere for the es- 4cape of excess gas. To prevent gas from escaping through duct 62 when there is no more than enough to operate thepapparatus, the duct is provided with a check valve. A suitable check valve may be formed by providing the fitting with a threaded bore 63 parallel to passage 53 and screwing a valve seat plug 64 into the'bore. The outlet duct is so positioned that its inner portion enters the bore below the seat, and its outer portion leaves the bore from above the seat. The outer end o the bore is closed by a plug Y66, and a ball 61 rests loosely on the valve seat. The Weight of the ball is such that it seats whenever the pressure of the ingoing gas starts to drop below that required for the apparatus and thereby prevents any of the gas from escaping. However, asv long as there is more tgas than needed the excess will escape through utlet duct 62 by unseating .the ball. 4

In order to keep a record of the number of analyses made so that the cartridge will be replaced at the proper time, a meter 68 is preferably attached to collar 3. This meter, which v is of well-known construction, is actuated by pins 69, projecting from plate 2, every time the collar is turned from analyzing to'purging position.

In analyzing a gaseous mixture with this apparatus, for example, exhaust gas of an internal combustion engine', passage 53 in cap 52 is connected by a hose or the like to the exhaust pipe. Disc i is turned relative to plate 2 to the purging position shown in Fig'. 9, and the bulb is compressed a few times to ilush air across both sides of the diffusion diaphragm. During this operation the exhaust gases entering barrel 5| leave it through passage 2.6, groove 36 and outlet 31 (Fig. 9) withoutv reaching the diffusion diaphragm.

purge it of the gases that were analyzed.

The disc is then turned to analyzing position,

as shown in Fig. 6, -wherein the chamber between.

ture diffuses through that diaphragm rapidly and creates a pressure that is registered by the' meter. As the amount of pressure created in this manner indicates the proportion of hydrogen in the mixture, the proportion of the other remaining constituentgases can be calculated;v From the various proportions of gases in the mixture it is possible to` tell how efciently the engine is operating. Preferably, the dial is calibrated in some such manner as indicated in Fig. v2 in order i `to give a direct reading of engine operating el- `ciency. After the reading has been taken, the

disc is turned back to its purging position and air is forced through the apparatus by the bulb to According to the provisions of the patent statf utes, I have explained the principle and mode of operation of my invention and have illustrated and describedy what Inow consider to represent its best embodiment. However, I desire to have it understood that, within the scope of the appended claims, the invention may be practiced otherwise than as specically illustrated and described. i

I claim:

1. A gas analyzer comprising a plate Khaving an inlet passage therethrough adapted to be' connected to a source of gas to be analyzed, a disc rotatably disposed against said plate in sealing engagement therewith and provided with an opening, a diffusion diaphragm spaced from said plate and closing the end of said opening adjacent thereto, a' pressure-actuated diaphragm closing the opposite end of said opening and spaced from the diffusion diaphragm, a meter operatively connected to said pressure diaphragm, said disc and plate being provided with passages connecting said inlet passage to the plate side of the dif-g fusion diaphragm, said passages being sealed from one another when the disc and plate are rotated relative to each other to inoperative position, said plate being provided with an outlet passage connecting said plate side of the diffusion diaphragm with the latmosphere at all times, and means for producing a current of air, said disc and plate ,being provided with ducts that register when the disc and.plate are 1n said inoperative position for connecting said means with both sides of the diffusion diaphragm and for connecting the pressure diaphragm side of said diffusion diaphragm with the atmosphere.

2. A gas analyzer comprising two plates disposed face to face in sealing engagement and adapted to be rotated relative to each other between operative and inoperative positions, one of means connected to the opposite end of said opening for indicating the pressure of gas diffusing through said diaphragm, and means for creating a current of air, said plates being provided with d lductsthat connect said air-creating means with lengagement therewith and provided with an opening, a diiusion diaphragm spaced from said plate and closing the end oisaid opening adja. cent thereto, a pressure-actuated diaphragm closing the opposite end of said opening and spaced from the diffusion diaphragm, a 'meter )operatively connected to said pressure diaphragm,

\said disc and plate being provided with passages connecting said inlet passage to the plate side of the diffusion diaphragm, `said passages being sealed from one another when the disc and plate are rotated relative to each other to inoperative position, said plate being provided with an` outlet passage connecting said plater side of the diffusion diaphragm with the atmosphere ati all times, and means for producing `a current of air, said disc and plate being provided with ducts that register only when the disc and plate are in said inoperative position for connecting said means with both sides of the diiusion diaphragm and for connecting the pressure diaphragm side of said diffusion diaphragm with the atmosphere.

-4. A gas analyzer comprising a plate having site end oi said opening for indicating changes in pressure in that opening, said disc and plate being provided with passages connecting ,said inlet passage to the plate side oi.' the diffusion diaphragm, said passages being sealed from vone another when the discv and plate are rotated relative to each other topinoperative positin, said plate being provided with an outlet passage connecting said plate side of the diiusion diaphragm with the atmosphere at all times. and means for producing a current of air, said disc and plate vbeing provided with ducts that register when the disc, and plate are in said inoperative position for connecting said means with both sides of the diiusion diaphragm and for connecting the side of said diaphragm adjacent said pressure indicating means with the atmosphere.

OWEN G. BENNETT. 

